Gap junction plasticity as a mechanism to regulate network-wide oscillations

Cortical oscillations are thought to be involved in many cognitive functions and processes. Several mechanisms have been proposed to regulate oscillations. One prominent but understudied mechanism is gap junction coupling. Gap junctions are ubiquitous in cortex between GABAergic interneurons. Moreover, recent experiments indicate their strength can be modified in an activity-dependent manner, similar to chemical synapses. We hypothesized that activity-dependent gap junction plasticity acts as a mechanism to regulate oscillations in the cortex. We developed a computational model of gap junction plasticity in a recurrent cortical network based on recent experimental findings. We showed that gap junction plasticity can serve as a homeostatic mechanism for oscillations by maintaining a tight balance between two network states: asynchronous irregular activity and synchronized oscillations. This homeostatic mechanism allows for robust communication between neuronal assemblies through two different mechanisms: transient oscillations and frequency modulation. This implies a direct functional role for gap junction plasticity in information transmission in cortex

Rôle hydrogéologique des linéaments structuraux en milieu cristallin et cristallophyllien : cas du bassin versant du Sassandra, Sud-Ouest de la Côte d’Ivoire

La zone d’étude est située en milieu tropical humide au sud-ouest de la Côte d’Ivoire dans les formations plutoniques et métamorphiques précambriennes. L’objectif est d’étudier l’effet des linéaments structuraux dans l’hydrodynamisme souterrain dans un tel environnement en se basant sur des données de télédétection, de forages, des teneurs SO42- et Cl- des eaux souterraines. Le traitement des images satellitaires a donné la carte des linéaments qui a servi au choix des sites d’échantillonnage d’eau souterraine et à l’individualisation des « blocs ». Les rapports de SO42- et Cl- a permis d’identifier les linéaments participant à la circulation de l’eau souterraine à l’échelle régionale. L’analyse des données géométriques des blocs et des débits des forages a permis de mettre en évidence le rôle hydrogéologique prépondérant des petits linéaments par rapport aux linéaments majeurs. Confirmant ainsi l’importance de l’horizon fissuré et la topographie dans l’écoulement souterrain en milieu de socle cristallin et cristallophyllien.Mots-clés: aquifères de socle, bloc, débit, horizon fissuré, hydrodynamisme.Hydrogeological role of structural lineaments in plutonic and metamorphic environment: Case of Sassandra Watershed (South-Western Côte d'Ivoire)The survey area is located south-west of Ivory Coast in Precambrian metamorphic and plutonic zone. The aim is to study the contribution of structural lineaments in the underground hydrodynamics in such environment. To highlight the network of kilometer-scale fractures in hard-rock, remote sensing techniques, drilling and concentrations SOSO42- and Cl- in groundwater were used. The map of lineaments obtained after processing of satellite images has been discretized into blocks aquifers which are delimited by opened or clogged fractures that can have a conducting or watertight function. Analysis of the geometric block parameters and the drilling instantaneous discharge helped highlight the leading role hydrogeological small fractures (fissured layer) compared to major lineaments in groundwater flow of in hard-rock. Thus confirming the importance of fissured topography and groundwater flow in crystallophyllian crystalline basement.Keywords: hard-rock aquifer, block, hydrodynamism, fissured zone, and yield

Évaluation de la potabilité chimique des eaux souterraines dans un bassin versant tropical :Cas du Sud-Ouest de la Côte d’Ivoire

L'etude propose un etat des lieux de la qualite chimique des eaux souterraines ainsi que leur situation vis-a-vis d'elements toxiques d'origine anthropique (nitrate et pesticides) dans la nouvelle boucle du cacao (Sud-Ouest de la Cote dfIvoire). Cinquante-six echantillons dfeau souterraine et de surface ont ete preleves au cours de deux campagnes de terrain puis analyses en se basant sur seize parametres physico-chimiques. Les resultats montrent que les eaux souterraines ont pour la majorite un pH neutre. Elles sont a 34% tres faiblement mineralisees ; seulement 21% presente une conductivite superieure a 500 ƒÊS.cm-1. Ces eaux sont pour la plupart bicarbonatees dont une moitie est alcaline et lfautre calco-magnesienne. La qualite chimique est satisfaisante pour 80% des eaux etudiees au regard des normes OMS. Certaines ont meme des teneurs voisines a certaines eaux minerales de commerce. En revanche, dfautres presentent des teneurs tres critiques en nitrate, en sulfate et en fer. Les fortes teneurs en nitrate proviennent des activites humaines demontrant que les ressources en eau de la region ne sont pas a lfabri dfune pollution par les pesticides qui sont fortement utilises dans les plantations de cacao, cafe, hevea et palmier a huile ainsi que dans les maraichers.Mots cles: Qualite physico-chimique, pesticides, nitrate, hydrochimie, Cote dfIvoire

Electroacoustic miniaturized DNA-biosensor

A micrometer-sized electroacoustic DNA-biosensor was developed. The device included a thin semi-crystalline polyethylene terephthalate (PET) dielectric layer with two Ag microband electrodes on one side and a DNA thiol-labeled monolayer adsorbed on a gold surface on the other. A resonance wave was observed at 29 MHz with a network analyzer, upon AC voltage application between the two Ag electrodes, corresponding to electromechanical coupling induced by molecular dipoles of the PET polymer chain in the dielectric layer. It was found that the device size and geometry were well adapted to detect DNA hybridization, by measuring the capacity of the resonance response evolution: hybridization induced polarization of the dielectric material that affected the electromechanical coupling established in the dielectric layer. The 0.2 mm2 sensor sensitive area allows detection in small volumes and still has higher detection levels for bioanalytical applications, the non-contact configuration adopted avoids electric faradic reactions that may damage biosensor sensitive layers, and finally, PET is a costless raw material, easy to process and well adapted for large scale production. The well-balanced technological and economic advantages of this kind of device make it a good candidate for biochip integration

The relationship between bi/multilingualism, nativeness, proficiency and multimodal emotion recognition ability

Aims and Objectives: The primary aim of this study is to investigate the relationship between visual–vocal–verbal emotion recognition ability (ERA) and multilingualism – that is, both bilingual first language (L1) acquisition and the level of multilingualism operationalised as the number of languages one can speak. Besides these two factors, we also consider nativeness and proficiency as possible predictors of ERA. Methodology: One-thousand-two-hundred-and-twenty participants completed a survey online consisting of a sociobiographical background questionnaire, an English lexical test and an emotion recognition test including six stimuli. For each of the six audiovisual recordings, participants had to indicate which emotion they thought the L1 English speaker was conveying – happiness, sadness, anger, (positive) surprise, fear, disgust or no/neutral emotion. Data and Analysis: An individual ERA score was calculated for each participant. Correlations between ERA and the different variables were computed – including interactions – and significant correlations were fed into a linear regression model. Findings: The number of spoken languages was unrelated to ERA in our sample. The data revealed an interaction between BFLA and nativeness: bi/multilingually raised English second or foreign language (LX) users outperformed monolingually raised LX users, but bi/multilingually raised L1 users of English scored lower than monolingually raised L1 users. Proficiency was significantly related to ERA. Originality: This study points to a bilingual advantage in emotion recognition in English for participants with specific linguistic profiles. Participants who grew up with two languages from birth had an advantage if it did not include English. The advantage seemed to be cancelled out among bi/multilingually raised English L1 users, possibly due to interferences from their other L1(s) or L1 culture(s). Significance: This study contributes to the scarce literature on bilingual advantage in the affective domain and offers a nuanced view on bilingualism and ERA

Characterization of primary human hepatocytes, HepG2 cells, and HepaRG cells at the mRNA level and CYP activity in response to inducers and their predictivity for the detection of human hepatotoxins

In the pharmaceutical industry, improving the early detection of drug-induced hepatotoxicity is essential as it is one of the most important reasons for attrition of candidate drugs during the later stages of drug development. The first objective of this study was to better characterize different cellular models (i.e., HepG2, HepaRG cells, and fresh primary human hepatocytes) at the gene expression level and analyze their metabolic cytochrome P450 capabilities. The cellular models were exposed to three different CYP450 inducers; beta-naphthoflavone (BNF), phenobarbital (PB), and rifampicin (RIF). HepG2 cells responded very weakly to the different inducers at the gene expression level, and this translated generally into low CYP450 activities in the induced cells compared with the control cells. On the contrary, HepaRG cells and the three human donors were inducible after exposure to BNF, PB, and RIF according to gene expression responses and CYP450 activities. Consequently, HepaRG cells could be used in screening as a substitute and/or in complement to primary hepatocytes for CYP induction studies. The second objective was to investigate the predictivity of the different cellular models to detect hepatotoxins (16 hepatotoxic and 5 nonhepatotoxic compounds). Specificity was 100% with the different cellular models tested. Cryopreserved human hepatocytes gave the highest sensitivity, ranging from 31% to 44% (depending on the donor), followed by lower sensitivity (13%) for HepaRG and HepG2 cells (6.3%). Overall, none of the models under study gave desirable sensitivities (80–100%). Consequently, a high metabolic capacity and CYP inducibility in cell lines does not necessarily correlate with a high sensitivity for the detection of hepatotoxic drugs. Further investigations are necessary to compare different cellular models and determine those that are best suited for the detection of hepatotoxic compounds

A chemical survey of exoplanets with ARIEL

Thousands of exoplanets have now been discovered with a huge range of masses, sizes and orbits: from rocky Earth-like planets to large gas giants grazing the surface of their host star. However, the essential nature of these exoplanets remains largely mysterious: there is no known, discernible pattern linking the presence, size, or orbital parameters of a planet to the nature of its parent star. We have little idea whether the chemistry of a planet is linked to its formation environment, or whether the type of host star drives the physics and chemistry of the planet’s birth, and evolution. ARIEL was conceived to observe a large number (~1000) of transiting planets for statistical understanding, including gas giants, Neptunes, super-Earths and Earth-size planets around a range of host star types using transit spectroscopy in the 1.25–7.8 μm spectral range and multiple narrow-band photometry in the optical. ARIEL will focus on warm and hot planets to take advantage of their well-mixed atmospheres which should show minimal condensation and sequestration of high-Z materials compared to their colder Solar System siblings. Said warm and hot atmospheres are expected to be more representative of the planetary bulk composition. Observations of these warm/hot exoplanets, and in particular of their elemental composition (especially C, O, N, S, Si), will allow the understanding of the early stages of planetary and atmospheric formation during the nebular phase and the following few million years. ARIEL will thus provide a representative picture of the chemical nature of the exoplanets and relate this directly to the type and chemical environment of the host star. ARIEL is designed as a dedicated survey mission for combined-light spectroscopy, capable of observing a large and well-defined planet sample within its 4-year mission lifetime. Transit, eclipse and phase-curve spectroscopy methods, whereby the signal from the star and planet are differentiated using knowledge of the planetary ephemerides, allow us to measure atmospheric signals from the planet at levels of 10–100 part per million (ppm) relative to the star and, given the bright nature of targets, also allows more sophisticated techniques, such as eclipse mapping, to give a deeper insight into the nature of the atmosphere. These types of observations require a stable payload and satellite platform with broad, instantaneous wavelength coverage to detect many molecular species, probe the thermal structure, identify clouds and monitor the stellar activity. The wavelength range proposed covers all the expected major atmospheric gases from e.g. H2O, CO2, CH4 NH3, HCN, H2S through to the more exotic metallic compounds, such as TiO, VO, and condensed species. Simulations of ARIEL performance in conducting exoplanet surveys have been performed – using conservative estimates of mission performance and a full model of all significant noise sources in the measurement – using a list of potential ARIEL targets that incorporates the latest available exoplanet statistics. The conclusion at the end of the Phase A study, is that ARIEL – in line with the stated mission objectives – will be able to observe about 1000 exoplanets depending on the details of the adopted survey strategy, thus confirming the feasibility of the main science objectives.Peer reviewedFinal Published versio

The SuperCam Instrument Suite on the Mars 2020 Rover: Science Objectives and Mast-Unit Description

On the NASA 2020 rover mission to Jezero crater, the remote determination of the texture, mineralogy and chemistry of rocks is essential to quickly and thoroughly characterize an area and to optimize the selection of samples for return to Earth. As part of the Perseverance payload, SuperCam is a suite of five techniques that provide critical and complementary observations via Laser-Induced Breakdown Spectroscopy (LIBS), Time-Resolved Raman and Luminescence (TRR/L), visible and near-infrared spectroscopy (VISIR), high-resolution color imaging (RMI), and acoustic recording (MIC). SuperCam operates at remote distances, primarily 2-7 m, while providing data at sub-mm to mm scales. We report on SuperCam's science objectives in the context of the Mars 2020 mission goals and ways the different techniques can address these questions. The instrument is made up of three separate subsystems: the Mast Unit is designed and built in France; the Body Unit is provided by the United States; the calibration target holder is contributed by Spain, and the targets themselves by the entire science team. This publication focuses on the design, development, and tests of the Mast Unit; companion papers describe the other units. The goal of this work is to provide an understanding of the technical choices made, the constraints that were imposed, and ultimately the validated performance of the flight model as it leaves Earth, and it will serve as the foundation for Mars operations and future processing of the data.In France was provided by the Centre National d'Etudes Spatiales (CNES). Human resources were provided in part by the Centre National de la Recherche Scientifique (CNRS) and universities. Funding was provided in the US by NASA's Mars Exploration Program. Some funding of data analyses at Los Alamos National Laboratory (LANL) was provided by laboratory-directed research and development funds

The Supercam Instrument Suite on the NASA Mars 2020 Rover: Body Unit and Combined System Tests

The SuperCam instrument suite provides the Mars 2020 rover, Perseverance, with a number of versatile remote-sensing techniques that can be used at long distance as well as within the robotic-arm workspace. These include laser-induced breakdown spectroscopy (LIBS), remote time-resolved Raman and luminescence spectroscopies, and visible and infrared (VISIR; separately referred to as VIS and IR) reflectance spectroscopy. A remote micro-imager (RMI) provides high-resolution color context imaging, and a microphone can be used as a stand-alone tool for environmental studies or to determine physical properties of rocks and soils from shock waves of laser-produced plasmas. SuperCam is built in three parts: The mast unit (MU), consisting of the laser, telescope, RMI, IR spectrometer, and associated electronics, is described in a companion paper. The on-board calibration targets are described in another companion paper. Here we describe SuperCam’s body unit (BU) and testing of the integrated instrument. The BU, mounted inside the rover body, receives light from the MU via a 5.8 m optical fiber. The light is split into three wavelength bands by a demultiplexer, and is routed via fiber bundles to three optical spectrometers, two of which (UV and violet; 245–340 and 385–465 nm) are crossed Czerny-Turner reflection spectrometers, nearly identical to their counterparts on ChemCam. The third is a high-efficiency transmission spectrometer containing an optical intensifier capable of gating exposures to 100 ns or longer, with variable delay times relative to the laser pulse. This spectrometer covers 535–853 nm (105–7070 cm−1 Raman shift relative to the 532 nm green laser beam) with 12 cm−1 full-width at half-maximum peak resolution in the Raman fingerprint region. The BU electronics boards interface with the rover and control the instrument, returning data to the rover. Thermal systems maintain a warm temperature during cruise to Mars to avoid contamination on the optics, and cool the detectors during operations on Mars. Results obtained with the integrated instrument demonstrate its capabilities for LIBS, for which a library of 332 standards was developed. Examples of Raman and VISIR spectroscopy are shown, demonstrating clear mineral identification with both techniques. Luminescence spectra demonstrate the utility of having both spectral and temporal dimensions. Finally, RMI and microphone tests on the rover demonstrate the capabilities of these subsystems as well